Alma brings the questions to a very individual level. Rather than passing judgment on how we think someone else might be living the gospel, Alma invites all to “imagine to yourselves that ye hear the voice of the Lord.” What will we be able to say in that day?
Alma warns us that we will not be able to lie. We cannot say that we have done righteous works, but not have actually done what was needed. This brings up the question of what those works might be. For Alma, it is a return to the question of exercising faith as noted in the discussion of verse 15. What matters is what we do, where our actions are a reflection of the type of person we have become.
The reason that we cannot be saved by claiming righteous works in the last day may be because we have not done them, or we have not allowed a mighty change of heart to change us and inform us of the reasons for doing righteous works. We can have a good relationship with a neighbor, either because we ignore them, or truly love them. Both might avoid a bad relationship, but only truly loving the neighbor is the result of the mighty change.